<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Lab2 - Formulario2</title>
	<script>
       function validar(){
         var n = document.f1.txtUsuario.value;         

         if (n == ""){
            alert('Ingrese Usuario');
            return false;
         }
         return true;
       }
    </script>

</head>
<body>

	<form action="" method="post" onsubmit="validar()" name="f1">	
		<h3>Formulario</h3>
		Usuario:	<input id="txtUsuario" type="text" name="txtUsuario" />
		<br/>
		Clave: <input id="txtClave" type="text" name="txtClave" />
		<br/>
		<input type="submit" value="Enviar"/>	
	</form>

</body>
</html>